140
FXUS10 KWNH 090416
PMDHMD
MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1216 AM EDT WED OCT 09 2019
VALID OCT 09/0000 UTC THRU OCT 12/1200 UTC
...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR
INGEST...
09/00Z MODEL EVALUATION WITH PREFERENCES AND FORECAST CONFIDENCE
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
..ENERGY AMPLIFYING OVER CENTRAL APPALACHIANS/MID-ATLANTIC
..DEEPENING SURFACE LOW PRESSURE OFF THE EAST COAST
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GENERAL MODEL BLEND UNTIL 12.00Z (NON-NAM THEREAFTER)
CONFIDENCE: SLIGHTLY ABOVE AVERAGE
THE 00Z GUIDANCE HAS NOT VARIED MUCH IN THE SHORT-TERM WITH THE
EVOLUTION OF THE DEEP OCCLUDED LOW SOUTHEAST OF LONG ISLAND. THIS
IS A SLIGHT SOUTHEAST SHIFT OVER THE 24HR PERIOD, BUT THERE IS
MUCH STRONGER AGREEMENT IN THE PLACEMENT/DEPTH OF THE SMALLER
SCALE FEATURES TO BUILD GREATER CONFIDENCE. AS THE CYCLONE
MATURES AND BREAKS DOWN, THE 00Z NAM BREAKS FROM CONSENSUS LIFTING
NORTH TOWARD NANTUCKET ISLAND. THE 00Z GFS, ALONG WITH THE 12Z
UKMET ARE STRONGER WITH A SECONDARY CYCLONE DEVELOPMENT AT THE
TRIPLE POINT, BUT OVERALL A NON-NAM BLEND IS SUPPORTED AT SLIGHTLY
ABOVE AVERAGE CONFIDENCE MAINLY AFTER 12.00Z (WITH GENERAL MODEL
BLEND SUPPORTED BEFORE).
..DEEP UPPER TROUGH/CLOSED LOW AMPLIFYING OVER THE WEST
..HIGH PLAINS CYCLOGENESIS
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: NON-GFS BLEND (MAINLY AFTER 11.12Z)
CONFIDENCE: SLIGHTLY ABOVE TO ABOVE AVERAGE
MODELS SHOW VERY GOOD TIMING IN THE LARGE SCALE WITH THE EVOLUTION
OF THE DEEP CLOSED CYCLONE IN THE CENTRAL PLAINS. THE 00Z GFS,
MUCH LIKE THE 18Z GFS, CONTINUES TO HINT AT A SLIGHTLY INCREASED
SPLIT BETWEEN THE POLAR AND SUBTROPICAL JET, MIDDAY FRI WHICH
LEADS TO AN OFF-BALANCE DOWNSTREAM DEVELOPMENT LATER FRIDAY INTO
SAT. AS SUCH THE, GFS IS A BIT SLOWER AND THEREFORE SOUTH WITH
THE SURFACE CYCLOGENESIS AND GREATER NEGATIVE TILT TO THE
UPPER-LEVEL CLOSED LOW. THE 12Z UKMET SHOWS GREATER NEGATIVE TILT
THAT THE ECMWF/CMC AND 00Z NAM, BUT THE OVERALL TIMING/PLACEMENT
OF THE FRONTAL ZONE AND QPF ARE MORE IN THE VEIN OF THE LATTER,
MAKING THE GFS THE SOLID OUTLIER. AS SUCH WILL PREFER A NON-GFS
BLEND AT SLIGHTLY ABOVE TO ABOVE AVERAGE CONFIDENCE.
...APPROACHING PACIFIC SHORTWAVE TROUGH WITH ATTENDANT SURFACE
WAVE AND FRONT BY SAT...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: 00Z NAM/12Z ECWMF BLEND W/LOW WEIGHTING INCL. OF 00Z
GFS
CONFIDENCE: AVERAGE
AN ELONGATED TROF ADVANCES ACROSS THE GULF OF AK FRI WITH GOOD
AGREEMENT. HOWEVER, A BREAK DOWN PHASE IN THE TROUGH OCCURS
THEREAFTER; WHERE INCREASED SHEARING BETWEEN THE NORTHERN AND
MIDDLE PACIFIC STREAMS, LEADS TO SOME AMPLIFICATION OF THE BASE OF
THE TROF. THE 00Z GFS, TYPICAL OF A POTENTIAL NEWER BIAS, IS
GENERALLY WEAKER AND LESS APT TOWARD SOME AMPLIFICATION, BUT HAS
GOOD TIMING WITHIN THE ENSEMBLE SUITE. THE 00Z NAM AND 12Z ECMWF
AND CMC, ALL SUGGEST A MORE SENSIBLE SMALLER COMPACT WAVE TO FORM;
HOWEVER, THE CMC IS UNCHARACTERISTICALLY ADVANCING TOWARD
VANCOUVER ISLAND, EARLY SAT AND SO IS NOT FAVORED AT THIS TIME.
THE 12 UKMET IS VERY AGGRESSIVE WITH THE CYCLOGENESIS AND IS NOT
PREFERRED. AS SUCH A 00Z NAM/12Z ECMWF BLEND IS PREFERRED WITH
SOME INCLUSION (AT LOWER WEIGHTING) OF THE 00Z GFS
MODEL TRENDS AT WWW.WPC.NOAA.GOV/HTML/MODEL2.HTML
500 MB FORECASTS AT WWW.WPC.NOAA.GOV/H5PREF/H5PREF.SHTML
GALLINA
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